It is well known that the exhaust gas from motor vehicles is considered a prime cause of air pollution. Accordingly, considerable activity has been and is now being directed to establishing prescribed standards of permissible emission levels of CO, HC, NO.sub.x, and CO.sub.2, and to methods and apparatus for evaluating the emissions to determine whether they fall within acceptable concentration ranges.
Among these activities, the Federal authorities have promulgated driving cycle tests for determining the presence of contaminants in engine exhaust emissions. Such tests are typical of urban driving by average motorists and are satisfactory for certification of new engines or engines in new vehicles. In the past, such tests required a great deal of time and were too complicated for mass vehicle inspection. This prompted the Federal Government to design and develop the IM240 emissions test. Which allows for emissions tests to be performed with minimum operator skill and experience. However, the IM240 test, and all other tests previously developed by the Federal Government are not designed to produce data from which the cause of the malfunction of the engine can be readily ascertained.
In light of heightened environmental awareness, it is anticipated that emission testing standards will be raised, causing an increase in the number of vehicles that fail such tests. Existing repair facilities will be grossly inadequate to handle such increases with the present hypothesis approach to pinpointing the cause of such failures. What is needed, in order to enable the necessary repairs to be made for any given vehicle found to have emission-related engine malfunction, is a quick method and simple means for evaluating the contaminants in the engine emissions to thereby provide an accurate diagnoses of the existing engine malfunction that is causing excessive contaminants. The diagnosis would inform the repairman or mechanic what the problem is so that malfunction could be corrected by proper adjustment or repair.
U.S. Pat. No. 3,998,095 for Method and Apparatus for Quickly Evaluating Engine Exhaust Gas Emissions, provides a system that provides engine malfunction diagnosis. However, the diagnosis opinion rendered does not have the level of detail that will be required in the future when emission testing standards are raised. Higher test standards, such as the EPA mandated IM240 emissions test will catch many engine malfunctions that go undetected by current emissions tests. There is a need for a system that utilizes the EPA mandated IM240 emissions test, which U.S. Pat. No. 3,998,095 specifically states that it does not use. This reference utilizes electronic logic circuits to represent truth charts to select a limited set (6 possible solution report sheets) of simplistic canned diagnosis for the myriad of possible engine malfunctions. Thus the drawback of such a system is that instead of accurate diagnoses of problems and specific solutions to problems, only generalized diagnosis of problem areas are provided.
For example if an engine failed an emission test as a result of abnormally high hydrocarbons, although the vehicle owner and test facilitator could be made aware of this fact, they could not be made aware of the cause of the problem (e.g., a plugged air filter, a need for spark plugs replacement, or simply use of bad gasoline). Therefore, it will be appreciated that the opinion provided by the system disclosed in U.S. Pat. No. 3,998,095 is simplistic and generic as to why the engine failed the emissions test. The opinion is only of use to the mechanic who needs minimal direction as to what needs to be repaired or checked. In addition, it fails to give a specific opinion as to what problems the engine had.
One major problem associated with this type of generic emission testing opinion, is that all vehicle owners who are not do-it-yourself mechanics remain uninformed as to what repairs specifically need to be performed on their vehicles in order to pass an emissions test. There is a need for an emission test opinion that informs the public as to what repairs specifically need to be performed, so that they can prevent unwarranted repairs.
In addition there is a need for a system that provides a closed loop on trouble-shooting engine problems and what fixes them. Such a system would be capable of learning over time and improving itself so that the system could provide more accurate diagnoses. It would be of great benefit to society and the automotive industry if there was a database that stored engine failure readings, the diagnosis for the problem, and the repaired engine readings along with what repairs were performed on the engine. Such a system could provide a means for monitoring automotive repairs. The information provided by the system would also allow the automotive industry to better understand what causes engine problems and how to fix them.
Another limitation to current emission testing, is that tests which are detailed enough to provide sufficient data for accurate pass/fail determinations and diagnosis are too time consuming. Typically, vehicles entering an emission testing station go through a schedule that captures a set of readings for that vehicle. Depending on the complexity of the analysis, there will be a considerable number of data points. Although it may not take significant time to determine whether the system fails the emission test, the diagnosis performed on those data points to determine what the problem is can take considerable time. Therefore, there is a need for a system which can perform a diagnosis on this data while adding negligible time to the emission testing process. The present invention addresses these draw backs.